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Chapter 2
Chemistry of Life
I. Elements
A. Element = substance that can’t be
broken down into simpler chemical
substances
1. C, H, O, & N make up more than 96% of
the mass of a human body.
2. Atom is the smallest particle of an element
that has the characteristics of that element.
3. Atoms are the basic building blocks of all
matter.
4. Structure of an atom
a. center of atom = nucleus
b. Nuclei
*contain positively charged
particles = protons (p+).
*contain particles that
have no charge =
neutrons (n0)
c. region of space surrounding nucleus
contains negatively charged particles =
electrons (e-)
• region of space = electron
cloud (dif. E levels)
5. Atoms contain equal numbers of electrons
& protons (no net charge).
B. Isotopes of an Element
1.Atoms of the same element have the
same number of protons, but
different numbers of neutrons.
II. Compounds/Bonding
A. Compound = subst that’s composed of
atoms of 2 or more different
elements that are chemically
combined
1.Example-salt (NaCl)
1 Na / 1 Cl
B. Covalent bonds
1. Attraction
of the positively
charged nuclei
for the shared,
negatively
charged
electrons holds
the atoms
together.
Hydrogen molecule
2. Example-2 H atoms
a. Molecule =
group of atoms
held together by
covalent bonds (no
overall charge)
Water
molecule
C. Ionic bonds
1. Atom (or group of atoms) that gains or
loses electrons has an electrical
charge = ion
a. Attractive
force between 2
ions of opposite
charge = ionic
bond
III. Chemical Reactions
A. Bonds are formed/broken &
diff. substs made
1. reactants vs. products
(r-left of arrow/p-right of arrow)
2. metabolism
IV. Mixtures / Solutions
A. Mixture = combi of substs in which
ind. components retain their
own properties
1. Solution = mixture in which 1 or more
substances (solutes) are distributed evenly in
another substance (solvent)
a. KoolAid powder = solute
b.Water = solvent
B. Acids & Bases
1.pH is a measure of how acidic/basic a
solution is.
a. dissociation of water into ions
2. pH scale ranges from 0 to 14
a. pH 7 = neutral
More acidic
Neutral
More basic
3. Substances with a pH below 7 are acidic.
a. Acid = substance that forms hydrogen
ions (H+) in water
b. hydronium ion (H3O+)
More acidic
Neutral
More basic
4. Substances with a
pH above 7 are basic.
a. Base = subst that forms
hydroxide ions (OH-) in
water
pH 11
V. Water
A. Water makes up 70 to 95 %
of most orgs.
1. versatile solvent
2. control liquid in expts
B. Water is Polar
1. Polar molecule = unequal distribution
of charge; each molecule has a positive
end & a negative end
a. 4 H bonds
VI. Role of Carbon
A. 2 C atoms can form various types of
covalent bonds—single, double or
triple
Single Bond
Double Bond
Triple Bond
B. Molecular Chains
1. C compounds vary greatly in size.
2. Form straight chains, branched chains, or
rings.
3. Sm molecules (monomers) bond together
to form chains = polymers
4. Reactions:
a. condensation/dehydration (lose water to make
polymers)
b. hydrolysis (add water to create monomers or
disassemble the polymers)
VII. Organic Compds (C)
A. Carbohydrates
1. Carbohydrate is a composed of C, H, &
O (ratio of about 2 hydrogen atoms & 1
oxygen atom for every carbon atom).
a. sugars/starches
b. reagents-Benedicts/Iodine
2. Simplest type of carbohydrate is a
monosaccharide (i.e. glucose, fructose).
a. Glucose C6H12O6 (memorize structural
formula)
b. 2 monos = dissaccharide
3.Largest carbohydrate molecules are
polysaccharides (polymers of monosac.).
B. Nucleic acids
1. Nucleic acid is a complex biomolecule that
stores cellular info in the form of a code
2. Nucleic acids are polymers made of smaller
subunits = nucleotides
3. Nucleotides are arranged in 3 groups—N base
(A/T/G/C/U), simple sugar, & phosphate group.
Phosphate
Sugar
Nitrogenous
base
4. DNA (deoxyribonucleic acid) & RNA
(ribonucleic acid) are impt. nucleic acids
Phosphate
Sugar
Nitrogenous
base
a. DNA-genetic info
*ATGC
b. RNA-making of proteins
*AUGC
C. Lipids
1. Lipids are made mostly of C & H with a small
amount of O. (ie. fats, oils, waxes)
2. Insoluble in water (nonpolar)
3. Saturated fats
a. single bonds
b. animal fats (solid)
4. Unsaturated fats
a. one or more double bonds
b. corn oil (liquid)
D. Protein
• 1.Protein is a large, complex polymer
composed of C, H, O, and sometimes
S.
•
a. reagent-Biuret
2. Basic building blocks of proteins are called
amino acids (aa).
3. 20 common aa’s
4. Peptide bonds = covalent bonds formed
between aa
5.Enzyme = protein that changes the rate of a
chemical reaction
a. speed reactions
(catalysts)
b. specific shape (like
lock & key)
c. enzymes have active sites & their
substrates (what ez reacts with) have
reactive sites
* ez + subs = ez + new prods
d. usually end in –ase
*lactase
e. denature ez = inactive
f. Induced fit theory
g. Lowers activation energy
h. Sensitive to temp, pH, & conc
Active
site-EZ
Substrate-reactive
site
The END!